Influence of three months of storage on the content of polyphenols and the rheological properties of chocolate liqueurs

Granter

University of ZagrebFaculty of Food Technology and Biotechnology

Lower level organizational units

Department of Food EngineeringLaboratory for Chemistry and Technology of Carbohydrates and Confectionery Products

Place

Zagreb

State

Croatia

Scientific field, discipline, subdiscipline

BIOTECHNICAL SCIENCESFood Technology

Study programme type

university

Study level

graduate

Study programme

Food Engineering

Academic title abbreviation

mag.ing.techn.aliment.

Genre

master's thesis

Language

Croatian

Defense date

2012-09-24

Parallel abstract (English)

The main goal of this research was to quantify the changes in the composition of polyphenols and antioxidant capacity of chocolate liqueurs produced of chocolates with different cocoa solids content (30, 32, 50 and 72%) in combination with different concentrations of ethanol (20, 25, 30 %) during three months of storage. The polyphenolic profile of the samples was determined by UV-VIS spectrophotometrical methods, as well as the antioxidant capacity which was evaluated by using ABTS (2,2-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) and DPPH [(2,2-diphenyl-1-picrylhydrazyl) assays. Rheological properties of the above mentioned were determined by Rheometric Scientific RM-180. By increasing the ethanol concentration, the share of extracted polyphenols increases; therefore the highest content of total phenols, flavan-3-ols and proanthocyanidins was determined in chocolate liqueurs produced from chocolate containing 72% of cocoa solids in combination with 30% ethanol. During the first three months of storage the share of total phenols, flavanoids and flavan-3-ols has decreased, while the share of proanthocyanidins and the antioxidant capacity increased significantly. The samples show features of pseudoplastic (32, 50, 72 %) and dilatant (30 %) liquids. The significant antioxidant potential of chocolate liqueurs indicates further development and research in order to produce functional products.